With continuous development of communications technologies, mobile communication has become a communication manner widely used by global users. Before establishing mobile communication, UE (User Equipment), such as a mobile terminal, needs to select a PLMN (Public Land Mobile Network) identifier and register successfully in an MSC (Mobile Switch Center), so that the UE can normally perform a mobile communication service, such as a voice service or a data service. To help the user equipment to rapidly select a PLMN identifier and register successfully, upon power-on, the user equipment preferentially selects a PLMN identifier stored in a card file EF_LOCI of a SIM (Subscriber Identity Module) card, that is, a PLMN identifier in RPLMN (Registered PLMN) information. The PLMN identifier is a PLMN identifier using which the user equipment initiates registration to the mobile switching center last time before last power-off.
In an existing 3GPP (3rd Generation Partnership Project) protocol, user equipment sends a selected PLMN identifier to a mobile switching center by using a location update request message; the mobile switching center returns a TMSI (Temporary Mobile Subscriber Identity) reallocation command, location update acceptance information, or location update rejection information to the user equipment according to the location update request message; and after acquiring the TMSI reallocation command or the location update acceptance information, the user equipment updates the selected PLMN identifier to the card file EF_LOCI, that is, the RPLMN information, of the SIM card, so that the user equipment can acquire the PLMN identifier directly from the card file EF_LOCI upon next power-on and initiate registration. It can be seen from above that the user equipment updates the PLMN identifier to the card file EF_LOCI at least twice, which reduces efficiency of registering the user equipment with the mobile network.